27" Cinema Display with "Thunderbolt" labeled cable?

In early 2011 I purchased a 27" Thunderbolt Display (this is how it was sold and marketed by Apple, btw) for use with my then-new Macbook Pro 15" Early 2011 (i.e. with Thunderbolt port). Monitor Serial # 2A0424CP6JL

The combo cable coming out of the monitor has a USB + power + "Thunderbolt" port (the label is clearly Thunderbolt NOT Mini Displayport). However, there are only three USB ports on the back of the monitor, not a Firewire port, nor another Thunderbolt port.

My question: I believe this monitor is nothing more than a rebranded 27" Cinema Display with a mini Displayport relabled with a "Thunderbolt" icon. Is there anyway to confirm that electrically, this is actually a Displayport and not a Thunderbolt port?

Thanx!

Michael

P.S. 30 days after I purchased this monitor, Apple "upgraded" it as documented in their store to include the 2nd Thunderbolt port and Firewire port. In other words, I think I have a rare transistional display that I can find no information anywhere on the web.